The number of different applications that can, or already do, benefit from using multiple digital processing nodes/devices is near limitless. A limiting factor in the performance of many such applications is the communication capacities between the digital processing nodes. Communication or routing networks can be used to provide the communication capacities between such processing nodes. A particular type of routing network is designed to handle individually-routable data units (sometimes referred to as packets) between nodes in the routing network. Each data unit can contain information identifying the destination node so that the routing network is able to route the data unit to the proper location. This, however, does not preclude data units from containing information that indicates an association between a set of data units.
Congestion in routing networks can be particularly troublesome in certain systems. For instance, a routing network provides a shared communication medium, and therefore, the occurrence of network congestion can have a global impact on the system performance. Network congestion can result from the offered throughput on a channel being greater than the bandwidth of the channel. In a lossy network system, network congestion can result in dropped packets, which would likely need to be retransmitted. In a lossless network system, network congestion can impact the rest of the network queues in a condition sometimes referred to as tree saturation. Without proper management of network congestion, traffic flow in the network can be detrimentally affected.